Wind turbines for power generation are well known in the art. In a common arrangement, a nacelle is mounted on a tower, with a rotor and blades being mounted on the nacelle. The rotor is mounted on a rotor shaft which is supported in the nacelle by a shaft housing.
In certain situations, the rotor must be stopped, maintained in position, or locked to prevent any rotary movement, for example so that maintenance work can be carried out on the rotor or nacelle. In general, rotor braking and locking mechanisms are known. In one previously considered arrangement, a locking hub is mounted on the rotor shaft. The locking hub is a radial flange with holes that can be engaged by locking pins mounted to and movable to and from the housing. In another previously considered system, a brake disc connectable to the rotor shaft has a series of serrations on its outer rim, and a brake block with two corresponding serrations is brought from a radial direction into contact with the brake disc serrations, to prevent rotary movement of the brake disc, thereby stopping the rotor rotating. However, these radially applied brakes require additional space in the housing, and may also be relatively insecure even at low rotor torques, without considering the increasing use of larger rotors for wind turbines.
In these (and other) situations, it may also be necessary for the rotor to be rotated somewhat, for example to move a section to be maintained to an area accessible for maintenance. Previously considered assemblies typically use an additional turning gear for providing such rotation; a turning gear engages with teeth provided on the rotor, to turn the rotor. Such turning gears are another additional component to be accommodated in limited space within the rotor housing. In addition, some previously considered systems provide only limited turning/rotating ability in the turning gear; others may not be applicable to the larger rotors in increasing use, as they may not provide sufficient torque to turn such larger rotors. Other previously considered techniques provide turning gears which are affixed or permanently applied or engaged to the corresponding rotor gear; this entails that in normal use the rotor may be impeded or at least rendered less efficient by the turning gear assembly.
The present invention aims to address these problems and provide improvements upon the known devices and methods.